JPS6024092B2 - Method for producing 2-hydroxyalkyl acrylate or 2-hydroxyalkyl methacrylate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing highly pure 2-hydroxyalkyl acrylate or 2-hydroxyalkyl methacrylate.

Specifically, the present invention involves esterifying acrylic acid or methacrylic acid and alkylene oxide having 2 to 4 carbon atoms in the presence of a catalyst to produce 2-hydroalkyl acrylate or 2-hydroalkyl acrylate with high purity and high yield. The present invention relates to a method for producing 2-hydroxyalkyl methacrylate. More specifically, the present invention provides as a catalyst a ferric salt of an aromatic carboxylic acid selected from the group consisting of ferric benzoate, ferric salicylate, ferric isophthalate, ferric orthophthalate. Provided is a method for producing 2-hydroxyalkyl acrylate or 2-hydroxyalkyl methacrylate, characterized in that the above esterification reaction is carried out in the presence of at least one species. 2-hydroxyalkyl acrylate or 2-hydroxyalkyl methacrylate (hereinafter referred to as 2-hydroxyalkyl (meth)acrylate).

) has traditionally been produced by an esterification reaction between acrylic acid or methacrylic acid (hereinafter referred to as (meth)acrylic acid) and alkylene oxide in the presence of a base catalyst such as a tertiary amine or an acid catalyst such as aluminum chloride. It is well known that However, both have long reaction times,
There are many difficult problems in industrial implementation, such as a large number of created organisms, low yield, easy coloring of the product, and corrosion of equipment. In recent years, it has been reported that iron compounds are effective as catalysts to solve these problems. In particular, ferric chloride (UK Patent No. 8)
71767), ferric sulfate and (meta)
Ferric salts of aliphatic carboxylic acids such as ferric acrylate (see British Patent No. 1,054,614) and ferric acetate are known to be effective. However, since the ferric chloride catalyst contains chloride ions, it not only causes alkylene chlorohydrin to form during the esterification reaction, but also poses major problems for industrialization, such as severe corrosion of the equipment.

Further, ferric sulfate has a negative effect on (meth)acrylic acid, has problems in activity and selectivity, and has the disadvantage that the yield cannot be fully satisfied. There are also many created alkylene glycol di(meth)acrylates (hereinafter referred to as gestals) and dialkylene glycol mono(meth)acrylates. Ferric (meth)acrylate is a compound that is unstable to moisture, making it difficult to prepare and handle pure ferric (meth)acrylate, and ferric acetate is a compound that is unstable to moisture. Not only does it have properties similar to ferric acid, but it also causes an exchange reaction of the ferric acid group in the esterification reaction,
The creation of created creatures due to this is unavoidable. In addition, as these iron salt catalysts, iron alkoxides (British Patent No. 8717
67) and iron acetylacetonate (see the specification of Japanese Patent Publication No. 43-26606) have also been proposed, but not only are the catalysts themselves expensive, but they also tend to react with moisture in the air and are difficult to handle. is difficult. Moreover, it has the disadvantage that its activity is not high enough and there are many created creatures such as gestel. Another method is to add iron powder to raw material (meth)acrylic acid, dissolve it, and use it as a catalyst.
138534), a method in which iron hydroxide is added and used as a catalyst (Japanese Patent Application Laid-Open No. 132518/1983),
However, in both cases, the preparation of the catalyst is complicated, and in the latter case, phosphoric acid is added to avoid scaling of the distillation vessel during distillation of the reaction product. There are drawbacks such as the need to remove iron compounds in advance in a precipitation furnace (see specification of Tokubatsu No. 39008/1983). The raw material (meth)acrylic acid and the product 2-hydroxyalkyl (meth)acrylate are extremely highly polymerizable compounds. Great care must be taken to prevent polymerization both during the esterification reaction and during purification. Since the ester has a relatively high boiling point and high polymerizability, simple flash distillation must be used to separate and purify it from the reaction product. Separation from living organisms will be incomplete, so a low production rate of created organisms in the reaction is an important requirement.
More importantly, it is required that the production of gestal, which is one of the by-products, be reduced. Gestel is 2
It has double bonds in its molecule that act as a crosslinking agent and cause gelation, causing not only polymerization loss during purification distillation but also major process troubles. Moreover, in the above-mentioned purification operation called flash distillation, there is a tendency for the target 2-hydroxyalkyl (meth)acrylate to be entrained and mixed into the product as it is. Therefore, in the esterification reaction, it is necessary to suppress the generation rate of gestel as much as possible, and it is most desirable to use a catalyst with good selectivity. The present invention satisfies the above conditions and provides an industrially advantageous method for producing 2-hydroxyalkyl (meth)acrylate that overcomes various drawbacks of iron-based catalysts.

One of the characteristics of the catalyst used in the present invention is that the (meth)
It has high solubility in acrylic acid and the reaction solution, there is no need for the trouble of dissolving the catalyst in the raw material (meth)acrylic acid, the reaction proceeds in a homogeneous system from the beginning of the reaction, and the amount of alkylene oxide added is extremely small. It has the advantage that the alkylene oxide recovery step can be substantially omitted.

Furthermore, scaling due to iron compounds in the distillation pot may be prevented during distillation. Another feature is that the catalyst performance is at a high level.

That is, the activity is high and the amount of gestal and dialkylene glycol mono(meth)acrylate created is small. That is, the object of the present invention is to carry out the esterification reaction in the presence of a catalyst that has good compatibility with (meth)acrylic acid as a raw material, has a high reaction rate, and has high catalytic activity and high selectivity. It is something. Still another object of the present invention is to perform simple distillation for purification without separating the catalyst from the reaction liquid obtained by the esterification reaction, thereby solving the complexity of the distillation process. - To provide an industrially advantageous method for producing hydroxyalkyl acrylate.

Specifically, according to the present invention, (meth)acrylic acid and carbon number 2
The alkylene oxide having 4 to 4 is a ferric salt of an aromatic carboxylic acid, particularly preferably selected from the group consisting of ferric benzoate, ferric salicylate, ferric orthophthalate, and ferric isophthalate. The present invention provides a method for producing 2-hydroxyalkyl (meth)acrylate, characterized in that the reaction is carried out at a temperature of 40 to 120q0 in the presence of at least one type of iron compound. Embodiments of the invention are described below.

In the present invention, at least one selected from the group consisting of ferric salts of aromatic carboxylic acids, particularly ferric benzoate, ferric salicylate, ferric orthophthalate, and ferric isophthalate is preferred. One type of iron compound is used as a catalyst, but it can also be used in the form of a mixture containing two or more types, and the appropriate amount used is in the range of 0.1 to 5% by weight based on the raw material (meth)acrylic acid. .

Examples of alkylene oxides used in the present invention include ethylene oxide, propylene oxide, butylene oxide, etc. having 2 carbon atoms.
~4 alkylene oxide.

These alkylene oxides are added in an amount equal to or more than the same molar amount, preferably 1.05 to 1.2 times the molar amount of (meth)acrylic acid. Esterification reaction is 4000 to 12
0oo, preferably from 50 to 100oo.

If the reaction temperature is lower than 4000, the reaction rate is insufficient;
Furthermore, at high temperatures of 120 μm or higher, it becomes difficult to suppress the polymerization reaction of (meth)acrylic acid, and the rate of formation of created organisms tends to increase.

The reaction of the present invention does not necessarily need to be carried out under pressure, but can be carried out immediately by dissolving the catalyst in (meth)acrylic acid, raising the reaction temperature while crossing the ocean, and supplying alkylene oxide in liquid or gaseous form under normal pressure. The reaction progresses.

After supplying a certain amount of alkylene oxide, it is desirable to maintain the reaction solution at a temperature of 50 to 100 oo for 0.5 to 5 hours until the reaction is completed. In addition, P-methoxyphenol, hydroquinone, phenothiazine, copper dialkyldithiocarbamate, tannic acid, etc. are added in advance to this reaction system as a polymerization inhibitor.

The present invention will be explained in more detail with reference to Examples below.

Example 1 216 ml of acrylic acid was placed in a 500 cc glass flask equipped with a reflux device and a concentrate device, and 0.2 ml of phenothiazine was added and dissolved while stirring at room temperature.

Furthermore, 9.7 hours of ferric benzoate was added to the solution, and the temperature was raised to 60 degrees. Then the temperature of the reaction system is 6
While the reactor was externally cooled with hot water so as not to exceed 0°C, 151.8 g of ethylene oxide was blown into the reactor in gaseous form over a period of 2.3 hours. Note that the ethylene oxide condensed in the reflux vessel was not returned to the reaction system but was recovered outside the system. The amount recovered was 6.6 hours. After the injection of ethylene oxide was completed, the reaction was further maintained at 5°C for 1 hour to complete the reaction. The reaction results are shown in Table 1. Each component in the reaction product liquid was analyzed by gas chromatography. Example 2 Into an autoclave (SUS316) having a capacity of 1 and equipped with a milling machine, 432 mm of acrylic acid and 0.4 mm of copper dibutyldithiocarbamate were charged, and 18.2 mm of ferric salicylate was added thereto.

The inside of the autoclave was replaced with nitrogen gas and sealed for 60 hours.
The temperature was raised to 0.00. Next, add 280 g of liquid ethylene oxide to 2. Inject while watching the sea bream at spot time, and after the injection is finished, 50o○
The reaction mixture was kept for 1 hour to complete the reaction. The reaction results are shown in Table 1. Example 3 The reaction was carried out in the same manner as in Example 2, except that ferrous orthophthalate was used as a catalyst.

The reaction results are shown in Table 1. Table 1 Comparative Example 1 Example 1 except that 6.5% of ferric sulfate was used as a catalyst
The same equipment and raw materials were used.

Ferric sulfate was hardly dissolved in acrylic acid and presented a heterogeneous system. Ethylene oxide gas was blown into the above mixture at a reaction temperature of 7500°C, and the reaction was carried out for 5 hours.
It took 05 evening. Ethylene oxide recovered outside the reaction system was 38
．． It was the 7th evening. After the injection of ethylene oxide was completed, the reaction was further carried out at 50 qo for 6 hours, and then rapidly cooled. The resulting reaction product liquid contained 1.3% by weight of unreacted acrylic acid, 0.2% by weight of Gestel, and 0.2% by weight of diethylene glycol monoacrylate. % by weight. Comparative Example 2 The same equipment and raw materials as in Example 1 were used except that ferric chloride was used as a catalyst.

2. Gaseous ethylene oxide was blown into the above mixture at a reaction temperature of 6 to 0. When reacted immediately, ethylene oxide was 18
It took 6 evenings. Ethylene oxide recovered outside the reaction system was 27.
It was two evenings. After the injection of ethylene oxide is completed, 5 more
After reacting for 1 hour at 0qo, it was rapidly cooled. Unreacted acrylic acid in the reaction product solution obtained was 0. % mother weight, diester 0.2% by weight, diethylene glycol monoacrylate 9. % by weight, and 2% by weight of ethylene chlorohydrin. Comparative Example 3 Example 1 except that ferric acid 4.4% was used as a catalyst
The same equipment and raw materials were used.

Ferric tate does not dissolve very well in acrylic acid. Ethylene oxide was blown in gaseous form at a reaction temperature of 75°C, and the reaction was carried out for 4 hours, and 196 hours of ethylene oxide was required. The amount of ethylene oxide recovered outside the reaction system was 41 days. After the injection of ethylene oxide was completed, the reaction was further carried out at 50 qo for 6 hours, and then rapidly cooled. The resulting reaction product solution contained 1.5% by weight of unreacted acrylic acid, 0.5% by weight of Gestel, and 10% by weight of diethylene glycol monoacrylate. % by weight.
Example 4 To the same autoclave as used in Example 2, 430 g of methacrylic acid and 0.4 g of copper dibutyldithiocarbamate were added, and further 16 g of ferric benzoate was added, and after purging the inside of the apparatus with nitrogen gas, The temperature was raised to 80° C. under sealed conditions.

Next, 235 ml of liquid ethylene oxide was injected over a period of 3 hours, and after the injection was completed, the reaction was kept at the same temperature for 2 hours to complete the reaction. 0 unreacted methacrylic acid in the obtained reaction product
．． Sword weight%, Gestel 0. The weight percentage was 7.5% by weight, and the content of diethylene glycol monomethacrylate was 7.5% by weight.

Example 5 Using the same reactor as in Example 2, acrylic acid 432
Add 0.49 yen and copper dibutyldithiocarbamate,
In addition, 18 g of ferric salicylate was added.

Claims (1)

[Scope of Claims] 1. A 2-hydroxyalkyl compound characterized by reacting acrylic acid or methacrylic acid with an alkylene oxide having 2 to 4 carbon atoms in the coexistence of a ferric salt of an aromatic carboxylic acid as a catalyst. A method for producing acrylate or 2-hydroxyalkyl methacrylate. 2. The method according to claim 1, wherein the catalyst is at least one selected from the group consisting of ferric benzoate, ferric salicylate, ferric isophthalate, and ferric orthophthalate.